The present invention relates to a terminal structure of electronic components for electronic appliances and a method of manufacturing the electronic components.
Japanese Patent Laid-open Publication No. H11-68284 discloses conventional chip electronic components which have improved reliability with respect to a portion soldered onto a circuit board.
FIG. 8 is a sectional view of a connecting portion of the conventional electronic component soldered onto the circuit board. As shown in FIG. 8, electrode 2 is formed on both side faces of electronic component 1, and two or more protrusions and recesses are provided on soldered portion 7 of electrode 2. Electronic component 1 is bonded onto land 4 on electronic circuit board 3 by solder 5, and solder 5 forms solder fillet 6.
Next, a conventional method of manufacturing the above chip electronic component which has improved reliability with respect to the soldered portion is described.
After forming electrode 2 on both side faces of electronic component 1, two or more protrusions and recesses 8 of 0.1 mm to 0.2 mm square are formed on soldered portion 7 of electrode 2. These protrusions and recesses 8 are processed on electrode 2 by etching for electronic components having electrode 2 less than 1 mm square, and by electric spark machining for those having electrode 2 above 1 mm square. The electronic component of the prior art thus improves reliability between land 4 and soldered portion 7 by forming protrusions and recesses 8.
The conventional chip electronic component as configured and manufactured above allows the improvement of reliability as described below.
When solder fillet 6 formed after soldering is exposed to repeated heating and cooling, the numerous 0.1 mm square to 0.2 mm square protrusions and recesses 8 formed on the surface of soldered portion 7 allow stress to be dissipated over the whole of soldered portion 7. This avoids the concentration of any stress on a limited area such as between land 4 and bottom face of electrode 2 or between land 4 and solder fillet 6. Stress concentration can thus be reduced by absorbing stress by the entire soldered portion 7. Accordingly, the reliability of soldered portion 7 is improved.
The conventional chip electronic component forms multiple 0.1 mm square to 0.2 mm square protrusions and recesses 8 on the surface of electrode 2. However, these protrusions and recesses for reducing stress concentration on electrode 2 surface cannot be formed on electronic components whose electrodes are only about 10 xcexcm thick, such as chip resistors and chip capacitors.
The present invention thus aims to improve the reliability of the soldered portion even for small electronic components having electrodes only about 10 xcexcm thick.
An electronic component of the present invention has a substrate on which one or more grooves are formed on its opposing side faces; electrodes formed on the groove and top and bottom faces of the substrate at a portion adjacent to the groove; and a circuit component formed between these electrodes. Side electrodes are also formed on the opposing side faces of the substrate at a portion other than the groove. This structure of the present invention enables to improve the reliability of a soldered area on small electronic components with electrodes only about 10 xcexcm thick such as chip capacitors and chip inductors.